In many mailing and shipping applications there is a need to protect the senders and recipients of mail items from errors, either inadvertent or deliberate. Errors can be a result of incorrect computer-driven data processing or human errors, as well as a result of deliberate attempts on the part of unscrupulous people to deceive or defraud the system. When errors occur the results can be tragic, such as, for example, when medicine is shipped and consequently consumed by a wrong recipient. In other instances errors result in significant and irrecoverable loss of financial resources, such as, for example, when valuable documents such as stock certificates are delivered to a wrong recipient. Yet in some other instances private and confidential documents may be sent to or received by a wrong recipient resulting in the loss of valuable data with multiple legal consequences. Thus, there is a need to positively identify (mutually authenticate) senders and recipients in mail communication systems. This means that senders want to have assurances that mail units sent have been received intact by their intended recipients. Likewise mail recipients want to be assured that mail units they received or about to receive were sent by their purported senders and include correct content, and not some possibly dangerous materials such as explosives, anthrax powder or a wrong medicine.
Mail communication systems typically consist of the sender (a party responsible for mail unit preparation and induction into a carrier distribution system), the carrier (the party responsible for processing and delivery of mail units) and the recipient (usually the intended recipient, a party to which a mail unit is supposed to be delivered in the absence of any errors). Carriers employ human personnel whose task is to deliver mail units to human recipients or deposit them into protected mail receptacles. Human clerks charged with delivery of mail units are referred to below as “Delivery Agents.” A mail piece, also referred to as a mail unit, can be of any type of a physically constrained item, such as a letter, flat, parcel, packet and the like. In the context of the present invention mail units always have valuable content, whose nature and description must be protected from unauthorized parties. It is desirable also to enable effective detection of the theft or unlawful substitution of the content of mail units, since such mail units are almost always exposed to a variety of carrier employees who may or may not have personal integrity.
Existing systems for mutually authenticating senders and recipients have various defects. Systems employed by the carriers frequently require that the recipient sign for the mail unit he/she is about to receive. The signature is facilitated through a portable communication device with a stylus and the data is sent for archival and dispute resolution to the carrier's data center. However, there is no connection between the signature and the mail unit content, and it is hard to ascertain the real identity of the recipient. For example, any member of the household or the office can receive and sign for the mail unit without any verification. Besides, devices employing stylus-enabled signatures are expensive and unreliable with a poor quality of data, making dispute resolution difficult at best. The privacy of data is hard to maintain when there is a requirement to protect the recipient from unauthorized data intrusion, such as, for example, when the mail unit is received not by the exact intended recipient, but by one of the members of the household or an office co-worker. The identity of the sender is typically revealed to an outside observer without opening the mail unit via the sender's origination address. And, when the delivery agent makes an error and brings a mail unit to the wrong address, it is sometimes difficult to detect because the incorrect recipient may not notice small differences in the address, especially when they are expecting mail units themselves. This has become more and more prevalent due to the wide proliferation of e-commerce making house and office delivery of packages an everyday occurrence.